As a related-art stacking-type header, there is known a stacking-type header including a first plate-shaped unit having formed therein a plurality of outlet flow passages and a plurality of inlet flow passages, and a second plate-shaped unit stacked on the first plate-shaped unit and having formed therein an inlet flow passage communicating with the plurality of outlet flow passages formed in the first plate-shaped unit, and an outlet flow passage communicating with the plurality of inlet flow passages formed in the first plate-shaped unit (for example, see Patent Literature 1).